Kidney Pt. 3 Flashcards
What solutes are secreted during tubular secretion?
- Creatinine.
- Drugs (ex: Penicillin).
- H+.
- K+.
- NH4+.
What are the 2 important outcomes of tubular secretion?
- Eliminate substances from the body.
- Secretion of H+ to control body pH.
What is reabsorption between adjacent tubule cells?
Paracellular reabsorption.
What is reabsorption through an individual tubule cell?
Transcellular reabsorption.
What is the concentration of Na+ ions in cells lining renal tubules?
Low concentration of Na+ ions, due to Na+/K+ ATPase pumps.
Where are Na+/K+ ATPase pumps located in cells that line the renal tubules?
On the basolateral membrane.
What does solute reabsorption drive?
Water reabsorption via osmosis.
*Obligatory.
Where does water reabsorption occur?
PCT and descending LOH.
What is the other method by which water is reabsorbed?
ADH acting on the kidney in the collecting duct.
How is Na+ transported during reabsorption?
- Symport.
- Antiport.
Where are Na+ symports located?
The apical membrane in the first half of the PCT.
What is an example of a Na+ symport?
The Na+-glucose symporter.
How does a Na+-glucose symport function?
2 Na+ and 1 glucose attach to the symporter protein and both move from the tubule fluid to the tubule cell.
What layer does glucose exit at?
The basolateral membrane via facilitated diffusion.
What is an example of an antiport?
The Na+/H+ antiport.
How does the the Na+/H+ antiport work?
Filtered Na+ moves down the concentration gradient into PCT cells, while H+ moves from the cytosol into the lumen. Na+ is reabsorbed and H+ is secreted into tubular fluid.
How is H+ produced in the PCT cells?
- Metabolic reactions.
- Peritubular blood.
- Tubular fluid.
What is the function of the enzyme carbonic anhydrase?
To catalyze the reaction of CO2 w/ H2O to form carbonic acid (H2CO3).
What does carbonic acid dissociate into?
- H+.
- HCO3-.
What % of filtered bicarbonate ions are reabsorbed?
80-90%.
